Composition for the manufacture of an ophtalmic lens comprising semi-conductive nanoparticles

ABSTRACT

A polymerizable liquid composition including semi-conductive nanoparticles for the manufacture of ophthalmic lenses. Specifically, polymerizable composition has at least one monomer or oligomer; at least one catalyst for initiating the polymerization of the monomer or oligomer; and semi-conductive nanoparticles, which are dispersed in the monomer or oligomer. The absorbance through a 2-millimeter-thick layer of the polymerizable composition is higher than 0.5 for each light wavelength ranging from 350 to λ cut , λ cut  being in the visible range, preferably in the range from 400 nm to 480 nm.

FIELD OF INVENTION

The present disclosure pertains to the field of polymerizable liquid composition for the manufacture of optical articles, especially ophthalmic lenses. The composition comprises semi-conductive nanoparticles with specific light absorbing properties. The disclosure also relates to the use of the composition and to the ophthalmic lens obtained from the composition.

BACKGROUND OF INVENTION

Light that reaches human eye comprises visible light, in wavelength range from about 380 to 780 nm, and non-visible light, which includes light in the ultraviolet range (UV-A and UV-B light from about 280 to 380 nm) and the infrared range (Near IR light from about 780 to 1400 nm).

UV light is known to be harmful to the human eye. In particular, it can induce ocular ageing which can lead to an early cataract or to more extreme disorders such as photokeratitis.

Blue light, also known as high-energy visible (HEV) light, corresponds to visible light in the blue-violet band between 380 and 500 nm. Prolonged exposure to blue light emitted from digital devices such as television, laptops, tablets and smartphones and fluorescent and LED lighting is harmful as blue light is able to reach the retina. Some specific ranges of blue light have been shown to cause photoretinitis; digital eyestrain, or computer vision syndrome which includes blurry vision, difficulty focusing, dry and irritated eyes, headaches, neck and back pain; disruption of the circadian rhythm; decreased melanin production; age-related macular degeneration; glaucoma; retinal degenerative diseases; breast and prostate cancer; diabetes; heart disease; obesity and depression. Blue light in the range from about 420 to 450 nm is believed to be especially harmful.

Damages from UV light and blue light can be prevented by incorporating light-absorbers in ophthalmic lenses. Usually, several additives are used, each absorber being efficient over a limited wavelength range.

Various methods can be used to prepare light-absorbing ophthalmic lenses. A first method is the impregnation of a polymerized lens in a bath containing a light-absorber as disclosed in European patent EP1085349. However, this method adds a step to the production process of the lens, which is not desirable in terms of cost and time.

A second method is the coating of a substance capable of absorbing light rays onto the surface of ophthalmic lenses as disclosed in U.S. Pat. No. 5,949,518. However, the incorporation of high amounts of light-absorbers in a coating weakens its mechanical properties.

The third method is the incorporation of a light-absorber in the bulk liquid formulation (i.e. before polymerization). Generally, lens obtained by this method are prone to undesirable yellowing due to degradation of the light-absorber during polymerization and/or upon ageing.

Document JP 2003 155415 discloses a polymerizable composition comprising a methacrylate monomer, AIBN (azobisisobutyronitrile) as a catalyst and CdS/SiO₂ semi-conductive nanoparticles. Document JP H09 227830 discloses a polymerizable composition comprising an alkoxysilane monomer, Magnesium perchlorate as a catalyst and SnO₂/ZnO semi-conductive nanoparticles, said composition is deposited as a coating on a polystyrene substrate. However, none of cited documents disclose a specific cut-off wavelength corresponding to the transition between an absorbance regime and a transmittance regime or the amount of semi-conductive nanoparticles in the composition. Both features have an impact on the filtering efficiency of such a polymerizable composition.

Indeed, interaction between radicals and light-absorbers during polymerization result in a yellow aspect of lenses. This yellowing effect is particularly apparent when high concentrations of catalysts are used to initiate polymerization, especially with monomers having weak reactivity such as allyl monomers.

Yellowing of the lens is undesirable for cosmetic reasons and because it can affect the colour perception of the wearer of lenses and eventually lower the transmittance of lenses.

In particular, for lenses absorbing blue light, two yellowing effects may be superposed. Interaction between radicals and the light-absorbing additive induces yellowing as stated above. For light passing through the lens, a part of blue light is absorbed which results in transmitted light appearing yellowish to the lens wearer.

Yellowing of the lens could be prevented if less catalyst was used but polymerization would not be complete and mechanical properties of the lens would not be acceptable. Protection of light absorbing additives in a capsule has been also proposed but lead to complex steps of synthesis and mixing.

There is thus a need for a polymerizable composition comprising a light-absorber for the manufacture of ophthalmic lenses, the light-absorber being not affected during polymerization and providing with a well-defined absorbance spectrum able to protect eye against high energy radiations and optimize colour perception.

The Applicant has found that this need could be met with semi-conductive nanoparticles dispersed in a polymerizable composition.

SUMMARY

The disclosure thus relates to a polymerizable composition for the manufacture of an ophthalmic lens, comprising:

-   -   a. at least one monomer or oligomer;     -   b. at least one catalyst for initiating the polymerization of         said monomer or oligomer; and     -   c. semi-conductive nanoparticles which are dispersed in said         monomer or oligomer. wherein the absorbance through a         2-millimeter thick layer of said polymerizable composition is         higher than 0.5 for each light wavelength ranging from 350 to         λ_(cut), λ_(cut) being in the visible range, preferably in the         range from 400 nm to 480 nm.

In an embodiment, monomer is an allyl monomer or an allyl oligomer.

In an embodiment, the catalyst is a free radical initiator.

In an embodiment, monomer is an alkoxysilane. In said embodiment, the catalyst may be a Lewis acid.

In an embodiment, the semi-conductive nanoparticles comprise a material of formula:

M_(x)Q_(y)E_(z)A_(w)  (I),

wherein: M is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; Q is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; E is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; A is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; and x, y, z and w are independently a decimal number from 0 to 5; x, y, z and w are not simultaneously equal to 0; x and y are not simultaneously equal to 0; z and w may not be simultaneously equal to 0.

In an embodiment, the semi-conductive nanoparticles are nanospheres, nanoplates or nanorods.

In an embodiment, the semi-conductive nanoparticles are core/shell particles or core/crown particles, the core being a different material from the shell or crown.

In an embodiment, the amount of semi-conductive nanoparticles in the composition is from 10 ppm to 10 wt %, based on the weight of the polymerizable liquid composition.

In an embodiment, the semi-conductive nanoparticles are capped with an organic layer or encapsulated in an inorganic matrix.

The disclosure also relates to a process for the preparation of the polymerizable composition as defined above, comprising the steps of:

-   -   a. providing a monomer or oligomer;     -   b. providing semi-conductive nanoparticles in the form of a         powder dispersible within said monomer or oligomer or in the         form of a dispersion of said semi-conductive nanoparticles in a         liquid dispersible within said monomer or oligomer;     -   c. providing a catalyst for initiating the polymerization of         said monomer or oligomer; and     -   d. mixing said monomer or oligomer, said semi-conductive         nanoparticles and said catalyst.

Another aspect of the disclosure relates to an ophthalmic lens obtained by curing the polymerizable composition as defined above.

Alternatively, the disclosure relates to an ophthalmic lens comprising:

-   -   a. an optical substrate; and     -   b. a coating obtained by curing the polymerizable composition as         defined above.

In an embodiment, the absorbance through a 2-millimeter thick ophthalmic lens is higher than 0.5 for each light wavelength ranging from 350 to λ_(cut), λ_(cut) being in the visible range, preferably in the range from 400 nm to 480 nm.

Definitions

In the present invention, the following terms have the following meanings:

-   -   “Absorbance” is the decimal logarithm of ratio I₀/I, where I₀ is         the intensity of light incident on a sample and I is the         intensity of light transmitted through said sample. In this         disclosure, absorbance is measured for a 2-millimeter-thick         sample. Absorbance is measured for wavelengths in UV and visible         range from 350 nm to 780 nm.     -   “Core/crown” refers to a heterostructure in which a central         nanoparticle: the core, is surrounded by a band of material         disposed on the periphery of the core: the crown.     -   “Core/shell” refers to a heterostructure in which a central         nanoparticle: the core, is embedded by a layer of material         disposed on the core: the shell. Two successive shells may be         laid, yielding core/shell/shell heterostructure. Core and shell         may have the same shape, for instance core is a nanosphere and         shell is a layer of essentially constant thickness yielding a         spherical core/shell nanoparticle. Core and shell may have         different shapes, for instance a dot—a nanosphere or a nanocube         or any other nanocluster—is provided as a core and shell is         grown laterally around the core, yielding an heterostructure         with shape of a nanoplate but comprising a dot inside the         nanoplate: the latter is named dot in plate thereafter. In some         embodiments, core and shell have different compositions. In         other embodiments composition varies continuously from core to         shell: there is no precise boundary between core and shell but         properties in centre of the core are different from properties         on the outer boundary of shell.     -   “Nanometric size” refers to a size of matter in which quantum         effects appear due to confinement. For semi-conductive         nanoparticles, nanometric size has to be defined with the         average Bohr radius of an electron/hole pair. Confinement is         effective for size in at least one dimension of the object below         20 nm, preferably below 15 nm, more preferably below 10 nm. The         stronger confinements are obtained with a size in at least one         dimension below 5 nm.     -   “Nanoparticle” refers to a particle having a size in at least         one of its dimensions below 100 nm. For a nanosphere, diameter         should be below 100 nm. For a nanoplate, thickness should be         below 100 nm. For a nanorod, diameter should be below 100 nm.     -   “Nanoplate” refers to a 2D shaped nanoparticle, wherein the         smallest dimension of said nanoplate is smaller than the largest         dimension of said nanoplate by a factor (aspect ratio) of at         least 1.5, at least 2, at least 2.5, at least 3, at least 3.5,         at least 4, at least 4.5, at least 5, at least 5.5, at least 6,         at least 6.5, at least 7, at least 7.5, at least 8, at least         8.5, at least 9, at least 9.5 or at least 10.     -   “Semi-conductive nanoparticles” refers to particles made of a         material having an electronic structure corresponding to         semi-conductive materials known in electronic industry but         having a nanometric size. Due to their specific electronic         structure, semi-conductive materials behave as high-pass         absorbing materials. Indeed, light having a wavelength more         energetic than band gap may be absorbed by the semi-conductive         material, yielding an electron/hole pair, an exciton, which         later recombine in the material and dissipate heat, or emit         light, or both. On the contrary, light having a wavelength less         energetic than band gap cannot be absorbed: semi-conductive         material is transparent for these wavelengths. In macroscopic         semi-conductive materials, visible light is generally absorbed         while near/mid infra-red light is not absorbed. When         semi-conductive particles have a nanometric size,         confinement—i.e. shape and nanometric size—governs electronic         structure following the rules of quantum mechanics and light         absorption may be limited to UV range or UV and high energy         visible light. Within this disclosure, semi-conductive         nanoparticles absorb light having a wavelength below a         threshold, this threshold being in the range of 350 nm-800 nm.

DETAILED DESCRIPTION

This disclosure relates to a polymerizable composition for the manufacture of ophthalmic lenses. The composition comprises at least one monomer or oligomer; at least one catalyst for initiating the polymerization of said monomer or oligomer; and semi-conductive nanoparticles which are dispersed in said monomer or oligomer.

Monomers and Catalysts

Monomers suitable for ophthalmic lenses may be classified in various chemical classes.

Allyl monomers or allyl oligomers are suitable for manufacture of ophthalmic lenses having a refractive index about 1.5-1.56. In this disclosure, an allyl monomer or allyl oligomer is a compound comprising an allyl group. Examples of suitable allyl compounds include diethylene glycol bis(allyl carbonate), ethylene glycol bis(allyl carbonate), oligomers of diethylene glycol bis(allyl carbonate), oligomers of ethylene glycol bis(allyl carbonate), bisphenol A bis(allyl carbonate), diallylphthalates such as diallyl phthalate, diallyl isophthalate and diallyl terephthalate, and mixtures thereof.

In an embodiment, the amount of said allyl monomers or allyl oligomers in the polymerizable composition may be from 20 to 99% by weight, in particular from 50 to 99% by weight, more particularly from 80 to 98% by weight, even more particularly from 90 to 97% by weight, based on the total weight of the composition. In particular, the polymerizable composition used for generating the matrix may comprise from 20 to 99% by weight, in particular 50 to 99% by weight, more particularly from 80 to 98% by weight, even more particularly from 90 to 97% by weight, based on the total weight of the composition, of diethylene glycol bis(allyl carbonate), oligomers of diethylene glycol bis(allyl carbonate) or mixtures thereof.

(Meth)acrylic monomers or (meth)acrylic oligomers are also suitable for manufacture of ophthalmic lenses having a refractive index about 1.5-1.56. In this disclosure, a (meth)acrylic monomer or (meth)acrylic oligomer is a compound comprising having acrylic or methacrylic groups. (Meth)acrylates may be monofunctional (meth)acrylates or multifunctional (meth)acrylates.

In an embodiment especially adapted for polymerization of allyl or (meth)acrylic monomers or oligomers, the catalyst meant for initiating polymerization is a free radical initiator. In a particular embodiment, catalyst is selected in the group consisting of a peroxodicarbonate, a peroxyester, a perketal, and mixtures thereof. Particularly suitable catalysts are selected in the group consisting of benzoyl peroxide, methyl ethyl peroxide, methyl ethyl ketone peroxide, di-t-butyl peroxide, lauroyl peroxide, acetyl peroxide, diisopropyl peroxydicarbonate, bis(4-t-butylcyclohexyl) peroxydicarbonate, t-butyl peroxy-2-ethylhexanoate, t-hexyl peroxy-2-ethylhexanoate, and mixtures thereof. In an alternative particular embodiment, catalyst is an azo compound selected from the group consisting of 2,2′-azobisisobutyronitrile, dimethyl 2,2′-azobis(2-methylpropionate), 2,2′-azobis(2-methylbutyronitrile), 2,2′-azobis(2,4-dimethylvaleronitrile), 4,4′-azobis(4-cyanopentanoic acid), and mixtures thereof.

Other examples of monomers or oligomers include compounds used to prepare polyurethane or polythiourethane materials. Thus, mixture of monomers or oligomers having at least two isocyanate functions with monomers or oligomers having at least two alcohol, thiol or epithio functions are suitable polymerizable compositions for manufacture of ophthalmic lenses. Generally, refractive index of such materials is in the range 1.6-1.74.

Monomer or oligomer having at least two isocyanate functions may be selected from symmetric aromatic diisocyanate such as 2,2′ Methylene diphenyl diisocyanate (2,2′ MD I), 4,4′ dibenzyl diisocyanate (4,4′ DBDI), 2,6 toluene diisocyanate (2,6 TDI), xylylene diisocyanate (XDI), 4,4′ Methylene diphenyl diisocyanate (4,4′ MDI) or asymmetric aromatic diisocyanate such as 2,4′ Methylene diphenyl diisocyanate (2,4′ MDI), 2,4′ dibenzyl diisocyanate (2,4′ DBDI), 2,4 toluene diisocyanate (2,4 TDI) or alicyclic diisocyanates such as Isophorone diisocyanate (IPDI), 2, 5(or 2, 6)-bis(iso-cyanatomethyl)-Bicyclo[2.2.1]heptane (NDI) or 4,4′ Diisocyanato-methylenedicyclohexane (H12MD I) or aliphatic diisocyanates such as hexamethylene diisocyanate (HDI) or mixtures thereof.

Monomer or oligomer having thiol function may be selected from Pentaerythritol tetrakis mercaptopropionate, Pentaerythritol tetrakis mercaptoacetate, 4-Mercaptomethyl-3,6-dithia-1,8-octanedithiol, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-bis[(2-mercaptoethyl)thiomethyl]-1,4-dithiane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane and mixture thereof.

Monomer or oligomer having epithio function may be selected from bis(2,3-epithiopropyl)sulfide, bis(2,3-epithiopropyl)disulfide and bis[4-(beta epithiopropylthio)phenyl]sulfide, bis[4-(beta-epithiopropyloxy)cyclohexyl]sulfide.

In an embodiment, the composition of the polymerizable composition yielding polyurethane or polythiourethane materials is stoichiometric, i.e. the number of isocyanate functions on monomers is substantially equal to the number of alcohol, thiol or epithio functions on monomers, so as to obtain a fully reticulated polymer.

In an embodiment especially adapted to compositions yielding polyurethane or polythiourethane materials, the catalyst meant for initiating polymerization is an organotin compound, and may be selected from dimethyltin chloride, dibutyltin chloride, and mixtures thereof.

Other examples of monomers or oligomers include compounds used to prepare materials usually known as Sol-Gels. Such monomers or oligomers may be selected from alkoxysilanes, alkylalkoxysilanes, epoxysilanes, epoxyalkoxysilanes, and mixtures thereof. These monomers or oligomers may be prepared in a solvent to form the polymerizable composition. Suitable solvents are polar solvents, such as water/alcohol mixtures.

Alkoxysilanes may be selected among compounds having the formula: R_(p)Si(Z)_(4-p) in which the R groups, identical or different, represent monovalent organic groups linked to the silicon atom through a carbon atom, the Z groups are identical or different and represent hydrolyzable groups or hydrogen atoms, p is an integer ranging from 0 to 2. Suitable alkoxysilanes may be selected in the group consisting of tetraethoxysilane Si(OC₂H₅)₄ (TEOS), tetramethoxysilane Si(OCH₃)₄ (TMOS), tetra(n-propoxy)silane, tetra(i-propoxy)silane, tetra(n-butoxy)silane, tetra(sec-butoxy)silane or tetra(t-butoxy)silane.

Alkylalkoxysilanes may be selected among compounds having the formula: R_(n)Y_(m)Si(Z₁)_(4-n-m) in which the R groups, identical or different, represent monovalent organic groups linked to the silicon atom through a carbon atom, the Y groups, identical or different, represent monovalent organic groups linked to the silicon atom through a carbon atom, the Z groups are identical or different and represent hydrolyzable groups or hydrogen atoms, m and n are integers such that m is equal to 1 or 2 and n+m=1 or 2.

Epoxyalkoxysilanes may be selected among compounds having the formula: R_(n)Y_(m)Si(Z₁)_(4-n-m) in which the R groups, identical or different, represent monovalent organic groups linked to the silicon atom through a carbon atom, the Y groups, identical or different, represent monovalent organic groups linked to the silicon atom through a carbon atom and containing at least one epoxy function, the Z groups are identical or different and represent hydrolyzable groups or hydrogen atoms, m and n are integers such that m is equal to 1 or 2 and n+m=1 or 2.

Suitable epoxysilanes may be selected from the group consisting of glycidoxy methyl trimethoxysilane, glycidoxy methyl triethoxysilane, glycidoxy methyl tripropoxysilane, α-glycidoxy ethyl trimethoxysilane, α-glycidoxy ethyl triethoxysilane, β-glycidoxy ethyl trimethoxysilane, β-glycidoxy ethyl triethoxysilane, β-glycidoxy ethyl tripropoxysilane, α-glycidoxy propyl trimethoxysilane, α-glycidoxy propyl triethoxysilane, α-glycidoxy propyl tripropoxysilane, β-glycidoxy propyl trimethoxysilane, β-glycidoxy propyl triethoxysilane, β-glycidoxy propyl tripropoxysilane, γ-glycidoxy propyl trimethoxysilane, γ-glycidoxy propyl triethoxysilane, γ-glycidoxy propyl tripropoxysilane, 2-(3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl) ethyltriethoxysilane.

In an embodiment especially adapted to compositions yielding Sol-Gel materials, the catalyst meant for initiating polymerization is a Lewis Acid. Carboxylates of metals such as zinc, titanium, zirconium, tin or magnesium; aluminum acetylacetonate Al(AcAc)₃ are suitable catalysts.

In an embodiment, the amount of alkoxysilanes is 0 to 90% by weight based on the theoretical dry extract of the polymerizable composition; the amount of alkyl alkoxysilanes is 20 to 90% by weight based on the theoretical dry extract of the polymerizable composition, the amount of catalyst is 0.1 to 5% by weight based on the theoretical dry extract of the polymerizable composition.

Semi-Conductive Nanoparticles

Materials may have various compositions and structures. Among mineral materials, some are electrically conductive, for instance metals. Some are electrically insulating, such as silicon oxide or tin oxide. Of particular interest in this disclosure are materials made of semi-conductive materials, well known in electronic industry. Semi-conductive materials may have a macroscopic size. If semi-conductive materials have a nanometric size, their electronic and optical properties are modified.

In this disclosure, semi-conductive nanoparticles bring especially interesting light absorbing properties to ophthalmic lenses comprising them. In particular, with proper selection of composition and structure of semi-conductive nanoparticles, light absorbers having a sharp transition between range of absorbed light (of high energy) and range of transmitted light (low energy) may be designed. Semi-conductive nanoparticles absorb light having a wavelength below a threshold, this threshold being in the range of 350 nm-800 nm.

FIG. 1.1 shows the generic absorbance curve of a polymerizable composition or material comprising semi-conductive nanoparticles as a function of wavelength of light from 350 nm to 780 nm: A(λ). The absorbance curve presents three zones. In low wavelength area, i.e. in UV light and high energy visible light, absorbance is high and/or is roughly constant, defining a first plateau P₁ with an average absorbance A₁. After first plateau P₁, absorbance decreases sharply to reach a value A₂ of a tenth of A₁: A₂=A₁/10, thus defining a decreasing zone D. The limit between plateau P₁ and decreasing zone D defines the wavelength of transition λ_(cut). After the decreasing zone D, absorbance may decrease and/or stabilize in a second plateau P₂, extending up to red end of visible light, namely 780 nm.

The width of decreasing zone D is generally less than 100 nm, preferably less than 50 nm, more preferably less than 40 nm, even preferably less than 30 nm.

While absorbance curves always have this generic shape, details vary with the nature of materials used and exact determination of λ_(cut) may be difficult.

In some embodiments, absorbance curve shows a clear maximum at the limit of P₁, and D, as shown on FIG. 1.1 . In this embodiment, λ_(cut) may be defined by the following formula, where λ_(cut) is in the decreasing zone D:

${A\left( \lambda_{cut} \right)} = \frac{\int_{350}^{k_{cut}}{{A(\lambda)}d\lambda}}{\lambda_{cut} - {350}}$

In this embodiment, λ_(cut) may be defined alternatively by the following formula for a local maximum:

$\left. \frac{{\partial\log}A}{\partial\lambda} \right)_{\lambda_{cut}} = 0$

In other embodiments, absorbance curve is monotonously decreasing slowly before decreasing sharply, as shown on FIG. 1.2 . In this embodiment, λ_(cut) may be defined by the lowest value of λ where decrease of absorbance become significant in decreasing zone, for instance where:

$\frac{{\partial\log}A}{\partial\lambda} < {{- 0},01}$

The different determinations of λ_(cut) proposed above give different but near values. In this disclosure, a value of λ_(cut) has to be considered as a rounded value with uncertainty of ±5 nm.

The value of λ_(cut) may be selected within UV or visible light range by a proper selection of semi conductive nanoparticles composition, shape and structure.

Composition

In one embodiment, the semi-conductive nanoparticles comprise a material of formula M_(x)Q_(y)E_(z)A_(w) (I), in which M is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; Q is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; E is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; and A is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof. x, y, z and w are independently a decimal number from 0 to 5; x, y, z and w are not simultaneously equal to 0; x and y are not simultaneously equal to 0; z and w may not be simultaneously equal to 0.

In particular, semi-conductive nanoparticles may comprise a material of formula M_(x)E_(y), in which M is Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Ge, Pb, Sb or a mixture thereof; and E is O, S, Se, Te, N, P, As or a mixture thereof. x and y are independently a decimal number from 0 to 5, with the proviso that x and y are not 0 at the same time.

In a specific embodiment, the semi-conductive nanoparticles comprise a material selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, HgO, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbS, PbSe, PbTe, GeS₂, GeSe₂, SnS₂, SnSe₂, CuInS₂, CuInSe₂, AgInS₂, AgInSe₂, CuS, Cu₂S, Ag₂S, Ag₂Se, Ag₂Te, FeS, FeS₂, InP, Cd₃P₂, Zn₃P₂, CdO, ZnO, FeO, Fe₂O₃, Fe₃O₄, Al₂O₃, TiO₂, MgO, MgS, MgSe, MgTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, TlN, TlP, TlAs, TlSb, MoS₂, PdS, Pd₄S, WS₂, CsPbCl₃, PbBr₃, CsPbBr₃, CH₃NH₃PbI₃, CH₃NH₃PbCl₃, CH₃NH₃PbBr₃, CsPbI₃, FAPbBr₃ (where FA stands for formamidinium), or a mixture thereof.

In a preferred configuration of this embodiment, the semi-conductive nanoparticles comprise CdS or ZnSe.

In a preferred configuration of this embodiment, the semi-conductive nanoparticles are ZnSe nanospheres or ZnSe nanoplates.

Shape

In this disclosure, semi-conductive nanoparticles may have different shapes, provided that they present a nanometric size leading to confinement of exciton created in the nanoparticle.

Semi-conductive nanoparticles may have nanometric sizes in three dimensions, allowing confinement of excitons in all three spatial dimensions. Such nanoparticles are for instance nanocubes or nanospheres also known as nanodots 1 as shown on FIG. 2 .

Semi-conductive nanoparticles may have a nanometric sizes in two dimensions, the third dimension being larger: excitons are confined in two spatial dimensions. Such nanoparticles are for instance nanorods, nanowires or nanorings.

Semi-conductive nanoparticles may have a nanometric size in one dimension, the other dimensions being larger: excitons are confined in one spatial dimension only. Such nanoparticles are for instance nanoplates 2 (also called nanoplatelets) as shown on FIG. 2 , nanosheets, nanoribbons or nanodisks.

According to one embodiment, the semi-conductive nanoparticles comprise at least 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% of semiconductor nanoplates.

The exact shape of semi-conductive particles defines confinement properties; then electronic and optical properties depending on composition of semi-conductive particle, in particular the band gap, then λ_(cut). It has been also observed that nanoparticles with a nanometric size in one dimension, especially nanoplates, present a sharper decreasing zone as compared to nanoparticles with other shapes. Indeed, width of decreasing zone is enlarged if nanometric size of nanoparticles fluctuates around a mean value. When nanometric size is controlled in only one dimension, i.e. for nanoplates, by a strict number of atomic layers, thickness fluctuations are almost null and transition between absorbing and non-absorbing state is very sharp. This leads to particularly effective light filters. In addition, semi-conductive particles are mineral materials able to withstand conditions in which organic light absorbers are degraded.

Structure

In an embodiment, semi-conductive nanoparticles are homostructures. By homostructure, it is meant that the nanoparticle is homogenous and has the same local composition in all its volume. In other words, such semi-conductive nanoparticles are core nanoparticles, as opposed to “core/shell” or “core/crown” nanoparticles, i.e. do not comprise a shell or a crown made of a different material than the core. This is advantageous as, adding a shell or crown on a nanoparticle may lead to a less abrupt transition between light absorption/transmission regimes.

In an alternative embodiment, semi-conductive nanoparticles are heterostructures. By heterostructure, it is meant that the nanoparticle is comprised of several sub-volumes, each sub-volume having a different composition from neighbouring sub-volumes. In a particular embodiment, all sub-volumes have a composition defined by formula (I) disclosed above, with different parameters, i.e. elemental composition and stoichiometry.

Example of heterostructure are core/shell nanoparticles as shown on FIG. 2 , the core having any shape disclosed above: nanosphere 11 or 44, nanoplate 33. A shell is a layer covering totally or partially the core: nanosphere 12, nanoplate 34 or 45. A particular example of core/shell heterostructure is a multi-layered structure comprising a core and several successive shells: nanospheres 12 and 13, nanoplates 34 and 35. For convenience, these multi-layered heterostructures are named core/shell hereafter. Core and shell may have the same shape—sphere 11 in sphere 12 for example—or not—dot 44 in plate 45 for instance.

Another example of heterostructure are core/crown nanoparticles as shown on FIG. 2 , the core having any shape disclosed above. A crown 23 is a band of material disposed on the periphery of the core 22—here a nanoplate. This heterostructure is particularly useful with cores being nanoplates and crown disposed on the edges of the nanoplate.

FIG. 2 shows clear boundaries between core on one hand and shell or crown on the other hand. Heterostructures also enclose structures in which composition varies continuously from core to shell/crown: there is no precise boundary between core and shell/crown but properties in centre of the core are different from properties on the outer boundary of shell/crown.

In an advantageous embodiment, semi-conductive nanoparticles have a largest dimension below 500 nm, in particular below 300 nm, ideally below 200 nm. Semi-conductive nanoparticles of small size do not induce light scattering when dispersed in a material having a different refractive index.

In a specific configuration of the previous embodiment, the spherical semi-conductive nanoparticles have a mean diameter ranging from 1 nm to 50 nm, preferably from 2 nm to 25 nm, more preferably from 2 nm to 10 nm, even more preferably from 4 nm to 8 nm.

In a specific configuration of the previous embodiment, semi-conductive nanoparticles have a mean thickness ranging from 0.1 nm to 20 nm, preferably from 0.5 nm to 10 nm, more preferably from 0.5 nm to 2.5 nm, a mean width ranging from 5 nm to 100 nm, preferably from 10 nm to 50 nm, more preferably from 10 nm to 30 nm, and/or a mean length ranging from 5 nm to 100 nm, preferably from 10 nm to 50 nm, more preferably from 10 nm to 30 nm.

Table 1 below discloses various semi-conducting nanoparticles suitable for use in this disclosure.

TABLE 1 λ_(cut) Homo/Hetero Dimensions Composition-formula (I) (nm) Shape structure (nm) Mx Qy Ez Aw cut 1 Sphere Homo 2.8 Cd 1 — Se l — 500 2 Plate Homo 1.2*15*25 Cd 1 — S 1 — 418 3 Plate Core/Crown Core: 1.2*15*15 Cd 1 — Se 1 — 407 Crown: 1.2*20*20 Cd 1 — S 1 — 4 Plate Core(Plate)/Shell Core: 1.2*10*15 Cd 1 — Se 1 — 602 Shell: 3*15*20 Zn 1 — S 1 — 5 Plate Core(gradient)/Shell Core: gradient Cd 1 — Se 0.5 S 0.5 430 (Dot in Plate) Shell: 1.2*15*15 Cd 1 — — S 1 6 Plate Core(Plate)/Shell Core: 1.2*10*15 Cd 1 — Se 0.3 S 0.7 478 Shell: 3*15*20 Cd 0.1 Zn 0.9 S 1 — 7 Sphere Homo 5.8 Zn 1 — Se 1 — 387 8 Plate Homo 1.9*15*30 Zn 1 — Se 1 — 382

Wavelength λ_(cut) of ZnSe nanospheres and ZnSe nanoplates described in Table 1 (lines 7 and 8) ranges from 400 nm to 480 nm after ligand exchange, as disclosed in the examples of the present disclosure.

In one embodiment, the semi-conductive nanoparticles are capped with an organic layer, an inorganic layer or a mixture thereof, and/or encapsulated in an inorganic matrix.

In an embodiment, semi-conductive nanoparticles are capped with organic compounds or inorganic compounds (referred as capping compounds), said organic or inorganic compounds forming an organic or inorganic layer at the surface of each nanoparticle. By capped, it is meant that organic compounds are adsorbed or absorbed on the surface of the semi-conductive nanoparticle. Capping compounds provide several advantages.

In particular, capping agent may behave as dispersing agents, avoiding semi-conductive nanoparticles agglomeration in polymerizable composition or during polymerization. Besides, capping agents may influence optical properties of semi-conductive nanoparticles as they modify boundary conditions of nanoparticles: but may be adjusted by selection of capping compounds.

Suitable capping compounds are ligands comprising at least one chemical moiety M_(A) having an affinity to the surface of the semi-conductive nanoparticle, by any kind of intermolecular interactions.

In particular, M_(A) may have an affinity for a metal element present at the surface of the semi-conductive nanoparticle. M_(A) may be a thiol, a dithiol, an imidazole, a catechol, a pyridine, a pyrrole, a thiophene, a thiazole, a pyrazine, a carboxylic acid or carboxylate, a naphthyridine, a phosphine, a phosphine oxide, a phenol, a primary amine, a secondary amine, a tertiary amine, a quaternary amine or an aromatic amine.

Alternatively, M_(A) may have an affinity for a non-metal element selected from the group of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I present at the surface of the semi-conductive nanoparticle. M_(A) may be an imidazole, a pyridine, a pyrrole, a thiazole, a pyrazine, a naphthyridine, a phosphine, a phosphine oxide, a primary amine, a secondary amine, a tertiary amine, a quaternary amine or an aromatic amine.

Ligands may comprise several chemical moieties M_(A), identical or different. Ligands may be a polymer having chemical moieties M_(A), identical or different, as pending groups along the polymer backbone or repeated groups in the polymer backbone.

Example of suitable inorganic caping compounds are inorganic ligands such as S²⁻, HS⁻, Se²⁻, Te²⁻, OH⁻, BF₄ ⁻, PF₆ ⁻, Cl⁻, Br⁻, I⁻, As₂Se₃, Sb₂S₃, Sb₂Te₃, Sb₂Se₃, As₂S₃ or a mixture thereof.

In an embodiment, semi-conductive nanoparticles are encapsulated within a matrix, forming capsules. By encapsulated, it is meant that semi-conductive nanoparticles are dispersed within an encapsulating material so that the encapsulating material covers all surface of semi-conductive nanoparticles. In other words, encapsulating material forms a barrier around semi-conductive nanoparticles. Such a barrier as several advantages. In particular, semi-conductive nanoparticles may be protected against chemicals, e.g. moisture, oxidants. Besides, semi-conductive nanoparticles that are not dispersible in a medium may be encapsulated in a material whose compatibility with said medium is good: the barrier behaves as a compatibilization agent. Last, encapsulated semi-conductive nanoparticles may be under the form of a powder dispersible in a medium instead of a dispersion in a solvent, thereby providing with easier handling in current processes.

Encapsulating material may be organic, in particular organic polymers. Suitable organic polymers are polyacrylates; polymethacrylates; polyacrylamides; polyamides; polyesters; polyethers; polyoelfins; polysaccharides; polyurethanes (or polycarbamates), polystyrenes; polyacrylonitrile-butadienestyrene (ABS); polycarbonate; poly(styrene acrylonitrile); vinyl polymers such as polyvinyl chloride; polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl pyridine, polyvinylimidazole; poly(p-phenylene oxide); polysulfone; polyethersulfone; polyethylenimine; polyphenylsulfone; poly(acrylonitrile styrene acrylate); polyepoxides, polythiophenes, polypyrroles; polyanilines; polyaryletherketones; polyfurans; polyimides; polyimidazoles; polyetherimides; polyketones; polynucleotides; polystyrene sulfonates; polyetherimines; polyamic acid; or any combinations and/or derivatives and/or copolymers thereof.

Encapsulating material may be mineral, in particular mineral oxides or mixture of mineral oxides. Suitable mineral oxides are SiO₂, Al₂O₃, TiO₂, ZrO₂, FeO, ZnO, MgO, SnO₂, Nb₂O5, CeO₂, BeO, IrO₂, CaO, Sc₂O₃, Na₂O, BaO, K₂O, TeO₂, MnO, B₂O₃, GeO₂, As₂O₃, Ta₂O5, Li₂O, SrO, Y₂O₃, HfO₂, MoO₂, Tc₂O7, ReO₂, Co₃O4, OsO, RhO₂, Rh₂O₃, CdO, HgO, Tl₂O, Ga₂O₃, In₂O₃, Bi₂O₃, Sb₂O₃, PoO₂, SeO₂, Cs₂O, La₂O₃, Pr6O11, Nd₂O₃, La₂O₃, Sm₂O₃, Eu₂O₃, Tb₄O₇, Dy₂O₃, Ho₂O₃, Er₂O₃, Tm₂O₃, Yb₂O₃, Lu₂O₃, Gd₂O₃, or a mixture thereof. Preferred mineral encapsulating materials are SiO₂, Al₂O₃ and ZnO. In particular, nanoparticles comprising Zn may be encapsulated by ZnO or SiO₂ and nanoparticles comprising Cd may be encapsulated by SiO₂, Al₂O₃ or mixture of SiO₂ and Al₂O₃.

In an advantageous embodiment, capsules are nanoparticles, with a largest dimension below 500 nm, in particular below 300 nm, ideally below 200 nm. Capsules of small size do not induce light scattering when dispersed in a material having a different refractive index.

The amount of semi-conductive nanoparticles in a capsule according to the present disclosure may be from 1.0 to 90% by weight, in particular from 2.5 to 50% by weight, more particularly from 3.0 to 25% by weight, based on the total weight of the capsule.

In this disclosure, semi-conductive nanoparticles are light absorbing agents. In this disclosure, absorbance of light of wavelength λ₀ by semi-conductive nanoparticles is defined as follows. Light of wavelength λ₀ is directed on a 2-millimeter-thick sample comprising semi-conductive nanoparticles. Intensity of directed light is I₀. The intensity I of light of wavelength λ₀ transmitted through the sample is measured. Absorbance light of wavelength λ₀ for is defined as the decimal logarithm of ratio I₀/I. Absorbance of 1 means that 9 out of 10 photons are absorbed by the sample. Absorbance of 0.3 means that 1 out of 2 photons is absorbed by the sample. Due to their electronic structure, semi-conductive nanoparticles behave as high pass filters: absorbance is high for wavelength of high energy, i.e. short wavelengths. On the contrary, absorbance for wavelength of low energy, i.e. long wavelengths, is low. The transition between both domains of high and low absorbance may be defined by the wavelength λ_(cut) defined above.

By proper selection of semi-conductive nanoparticles, λ_(cut) may be selected in the UV-visible range, i.e. between 350 nm and 780 nm. In an embodiment, λ_(cut) is in the visible range, i.e. between 380 nm and 780 nm. In a particular embodiment, λ_(cut) is in the blue part of visible range, i.e. between 400 nm and 480 nm, allowing for attenuation of blue light. In another particular embodiment, λ_(cut) is in the yellow-green part of visible range, i.e. between 480 nm and 600 nm, allowing for attenuation of blue and yellow light.

Polymerizable Composition

This disclosure relates to a polymerizable composition for the manufacture of ophthalmic lenses. The composition comprises at least one monomer or oligomer; at least one catalyst for initiating the polymerization of said monomer or oligomer; and semi-conductive nanoparticles which are dispersed in said monomer or oligomer.

The polymerizable composition may further comprise additives in conventional proportions. These additives include stabilizers such as antioxidants, UV light absorbers, light stabilizers, anti-yellowing agents, adhesion promoters, dyes, photochromic agents, pigments, rheology modifiers, lubricants, cross-linking agents, photo-initiators fragrances and pH regulators. They should neither decrease the effectiveness of polymerization nor deteriorate optical properties of the ophthalmic lens.

The polymerizable composition may also comprise colour balancing agents. Such additives are intended to lower the residual colour of ophthalmic lenses. Typically, dyes and/or pigments are used as colourants. These colourants being absorbent in the complementary colour of blue, a low coloured polymerizable composition is obtained, at the expense of a lowering of lightness. Indeed, polymerizable composition will appear slightly grey, i.e. not coloured.

In an advantageous embodiment, the polymerizable composition does not comprise additional UV light absorbers. Indeed, semi-conductive nanoparticles present a significant absorbance for light wavelength ranging from 280 nm to λ_(cut). When λ_(cut) is selected in the visible range, the whole UV-light ranging from 280 nm to 380 nm is absorbed by semi-conductive nanoparticles and no more UV light absorbers are required in the polymerizable composition.

The polymerizable composition may further comprise a solvent, provided that polymerization is not hindered by the solvent. Solvent may be selected from polar solvents, like water, an alcohol, or water/alcohol mixtures, preferably an alcohol, e.g. methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amylic alcohol, isoamylic alcohol, sec-amylic alcohol, tert-amylic alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, 1-methoxy-2-propanol n-hexanol, cyclohexanol, ethyl cellosolve (monoethoxy ethylene glycol), and ethylene glycol.

The amount of monomer or oligomer according to the present disclosure may be from 20 to 99% by weight, in particular from 50 to 99% by weight, more particularly from 80 to 98% by weight, even more particularly from 90 to 97% by weight, based on the theoretical dry extract of the composition.

By the theoretical dry extract of the composition, it is meant the weight of the composition from which all solvent and volatile moieties released during polymerization, e.g. cleavable alkyl substitutes of alkylsilanes, are removed.

The amount of catalyst in the polymerizable composition according to the present disclosure may be from 0.5 to 5.0% by weight. For allylic, methacrylic and other monomers polymerizable by radical, addition or condensation process, the amount of catalyst in the polymerizable composition may be in particular from 2.5 to 4.5% by weight, more particularly from 3.0 to 4.0% by weight, based on the theoretical dry extract of the composition. For Sol-Gel polymerizable composition, the amount of catalyst in the polymerizable composition may be in particular from 0.75 to 2.5% by weight, more particularly from 0.5 to 1.5% by weight, based on the theoretical dry extract of the composition.

The amount of semi-conductive nanoparticles according to the present disclosure may be from 10 ppm to 10% by weight, in particular from 10 ppm to 1% by weight, in particular from 20 ppm to 0.5% by weight, more particularly from 25 ppm to 0.25% by weight, based on the theoretical dry extract of the composition. In this disclosure, the organic material that is used to cap semi-conductive nanoparticles or the material that is used to encapsulate semi-conductive nanoparticles is not included in the amount of semi-conductive nanoparticles. For the sake of clarity, a polymerizable composition comprising 1% weight, based on the theoretical dry extract of the composition, of aggregates comprising 30% weight of semi-conductive nanoparticles embedded in 70% weight of a mineral matrix, comprises 0.3% weight of semi-conductive nanoparticles, based on the theoretical dry extract of the composition.

In one embodiment, semi-conductive nanoparticles are uniformly dispersed in the polymerizable composition, i.e. each nanoparticle is separated from its nearest neighbour nanoparticle by at least 5 nm, preferably 10 nm, more preferably 20 nm, even more preferably 50 nm, most preferably 100 nm. In other words, semi-conductive nanoparticles are not aggregated in the polymerizable composition. Advantageously, the farther away the particles, the lower the diffusion.

In an embodiment, the semi-conductive nanoparticles comprised in the polymerizable composition have the same formula (I), shape and structure.

In another embodiment, the semi-conductive nanoparticles comprised in the polymerizable composition have different formula (I) and/or different shape and/or different structure. In this embodiment, absorbance of the polymerizable composition may be adjusted by superposition of absorbance of each type of semi-conductive nanoparticles, as taught by Beer-Lambert law.

In this embodiment, the decreasing zone of absorbance curve may be more complex, with a first decrease, then an intermediate plateau, then a second decrease as shown on FIG. 1.2 . Hence, two decreasing zones D₁ and D₂ may be defined, each decreasing zone having a width of less than 100 nm, preferably less than 50 nm, more preferably less than 40 nm, even preferably less than 30 nm. Besides A₂ as defined above still apply and corresponds to two successive decreases.

More than two decreasing zones may be obtained and defined by analogy with the embodiment with two decreasing zones.

Absorbance of a polymerizable composition is measured on a 2-millimeter-thick sample of polymerizable composition comprising semi-conductive nanoparticles. In an embodiment, absorbance is higher than 0.5, preferably 1, more preferably 1.5 for each light wavelength ranging from 350 nm to λ_(cut). λ_(cut) may be in the visible range, preferably in the range from 400 nm to 500 nm, from 400 nm to 460 nm, from 400 nm to 430 nm, from 460 nm to 500 nm, or from 460 nm to 480 nm.

In one embodiment, absorbance of the polymerizable composition or of the ophthalmic lens has:

-   -   a local maximum absorbance of highest wavelength in the range         from 350 to 500 nm, said local maximum having an absorbance         value A_(max) for a wavelength λ_(max),     -   a value of 0.9A_(max) for a wavelength λ_(0.9), λ_(0.9) being         greater than λ_(max);     -   a value of 0.5A_(max) for a wavelength λ_(0.5), λ_(0.5) being         greater than λ_(0.9); and wherein |λ_(0.5)−λ_(0.9)| is less than         15 nm.

In a preferred configuration, |λ_(0.5)−λ_(0.9)| is less than 10 nm, or less than 5 nm.

In an embodiment, absorbance of the polymerizable composition or of the ophthalmic lens has a value of 0.1A_(max) for a wavelength λ_(0.1), λ_(0.1) being greater than λ_(0.9); and wherein |λ_(0.1)−λ_(0.9)| is less than 30 nm, preferably less than 20 nm, more preferably less than 10 nm.

Process of Preparation of Polymerizable Composition

This disclosure also relates to the process for the preparation of the polymerizable composition as defined above.

In a first step, a monomer or oligomer is provided. When the polymerizable composition comprises several monomers or oligomers, said monomers or oligomers may be provided as a mixture or as separate compositions.

In a second step, semi-conductive nanoparticles are provided. To ensure adequate dispersion in the polymerizable composition, i.e. in monomers or oligomers, semi-conductive nanoparticles may be in the form of a powder dispersible in monomers or oligomers. Alternatively, semi-conductive nanoparticles may be dispersed in a liquid, such as a solvent, said liquid being dispersible within said monomer or oligomer.

In a third step, a catalyst is provided.

In a fourth step, monomer or oligomer, semi-conductive nanoparticles and catalyst are mixed together to yield a homogeneous polymerizable composition. Mixing process may be realized in any order. In some embodiments, polymerization begins as soon as monomers or oligomers are mixed with catalyst: in this case, catalyst is added last. In some embodiment, at least two monomers or oligomers having different chemical functions are co-polymerized and polymerization begins as soon as monomers or oligomers are mixed with catalyst: in this case a composition comprising one monomer and catalyst may be prepared, then mixed last with other monomers.

The polymerizable composition obtained may be stored or used immediately.

Ophthalmic Lens

An ophthalmic lens is obtained by polymerization of polymerizable composition.

In an embodiment, the polymerizable composition may be casted into a mould, then polymerized. Polymerization may be induced by heating, by UV-visible light radiations, by actinic radiations or by a combination thereof: this step is also referred to as curing step. After curing and demoulding, a lens is obtained, whose optical surfaces have been defined by mould surfaces and whose optical properties results from composition of polymerizable composition. Curing conditions are well known and allow to obtain lenses without defects, in particular without bubbles and inhomogeneities in refractive index in the volume of the lens. The resulting polymerized material has a thickness ranging from 1 mm to 20 mm, preferably from 1 mm to 10 mm.

In another embodiment, an ophthalmic substrate, for instance a lens, with adequate optical properties is provided. A layer of polymerizable composition is applied on the substrate, then cured, yielding a coating. This embodiment is advantageous as a same polymerizable composition may be applied on different substrates. For instance, the same polymerizable composition may be used to coat lenses of refractive index 1.5 based on allylic monomers, in particular diethylene glycol bis allyl carbonate; lenses of refractive index 1.56 based on (meth)acrylic monomers; lenses of refractive index above 1.67 based on polythiourethane polymers and/or lenses of refractive index 1.59 based on thermoplastic polycarbonate.

In another embodiment, an ophthalmic substrate, for instance a lens, with adequate optical properties is provided. A dispersion of semi-conductive nanoparticles in a solvent is applied on the substrate, then dried, resulting in a thin layer of nanoparticles deposited on the ophthalmic substrate. Then, a polymerizable composition comprising only monomers or oligomers, catalyst and optionally solvent as disclosed above is applied on the substrate, then cured. The resulting coating contains semi-conductive nanoparticles and is similar to the coating disclosed above.

In a preferred configuration of this embodiment, the resulting coating has a thickness ranging from 0.5 μm to 20 μm, preferably from 1 μm to 15 μm, more preferably from 1 μm to 10 μm, most preferably from 1 μm to 8 μm.

In previous embodiments, nanoparticles may be capped or encapsulated in a matrix as disclosed above.

Ophthalmic lenses should have specific optical properties. In particular, ophthalmic lenses must be transparent. By transparent, it is meant two properties. First, light scattering by ophthalmic lenses should be low, typically below 1% as measured with standard haze measurement according to ASTM D1003-00, preferably below 0.8%, even preferably below 0.5%. Second, the shape of an object seen throughout an ophthalmic lens should be unaltered, in the sense that the wearer of said ophthalmic lenses can recognize an object when looking through them. In this disclosure, transparency is not related to the absorbance of visible light. In other words, an ophthalmic lens may be transparent and coloured.

In this disclosure, ophthalmic lenses comprise semi-conductive nanoparticles. Hence, ophthalmic lenses show absorbance of light. Absorbance for an ophthalmic lens is defined as for a polymerizable composition, except that sample is a 2-millimeter-thick polymerized material comprising semi-conductive nanoparticles or an optical substrate coated with a 5-micrometer-thick polymerized material comprising semi conductive nanoparticles.

Then, ophthalmic lenses behave as high pass filters: absorbance is high for wavelength of high energy, i.e. short wavelengths. On the contrary, absorbance for wavelength of low energy, i.e. long wavelengths, is low. The transition between both domains of high and low absorbance may be defined by the wavelength λ_(cut) for which absorbance is higher than 0.5, preferably 1, more preferably 1.5 for each light wavelength ranging from 350 nm to λ_(cut).

By proper selection of semi-conductive nanoparticles, λ_(cut) may be selected in the UV-visible range, i.e. between 350 nm and 780 nm. In an embodiment, λ_(cut) is in the visible range, i.e. between 380 nm and 780 nm.

In a particular embodiment, λ_(cut) is in the blue part of visible range, i.e. between 400 nm and 480 nm, allowing for attenuation of blue light. Such ophthalmic lenses are particularly suitable for night drivers, as blue light emitted by car headlamps is becoming increasingly rich in blue light which is strongly scattered. Such ophthalmic lenses are also particularly suitable for intense users of digital devices, i.e. computers, smartphones and more generally devices with a digital display; as blue light emitted by displays is now suspected to be source of various troubles including circadian rhythm and age-related macular degeneration inter alia.

In another particular embodiment, λ_(cut) is in the yellow-green part of visible range, i.e. between 480 nm and 600 nm, allowing for attenuation of blue and yellow light. Such ophthalmic lenses are particularly suitable for elderly people, who are usually very sensitive to central green spectrum of daylight. Such ophthalmic lenses are also particularly suitable for colour-blind people: a proper selection of λ_(cut) between the sensitivity peaks of green and red colours, for instance about 580 nm, allows to restore colour disambiguation.

Luminescent Semi-Conductive Nanoparticles

In an embodiment, semi conductive nanoparticles are luminescent. When irradiated with high energy radiation, an exciton is formed in the nanoparticle, which eventually relax by emission of a photon of energy corresponding to the band-gap of semi-conductive nanoparticle.

A lens comprising a luminescent semi-conductive nanoparticle may then be authenticated by presence of a specific light emission.

A mixture of luminescent semi-conductive nanoparticles having different emission wavelength could be used to provide a code of authentication, for industrial purpose, for customer guarantee or for counterfeiting identification of lenses.

Ideally, UV light absorption properties may be brought by non-luminescent semi-conductive nanoparticle and less than 5% weight of luminescent semi-conductive nanoparticle as compared to weight of non-luminescent semi-conductive nanoparticle may be added for authentication purpose.

Besides, luminescent semi-conductive nanoparticles may be used as colour balancing agents. In this case, a part of UV light absorbed by semi-conductive nanoparticles may be emitted in the visible light, especially in the blue-violet range of visible light, so as to balance the yellowing effect induced by absorption of blue-violet light by semi-conductive nanoparticles.

While various embodiments have been described and illustrated, the detailed description is not to be construed as being limited hereto. Various modifications can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the disclosure as defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the generic absorbance of a polymerizable composition or material comprising semi conductive nanoparticles (logarithm scale) as a function of wavelength of light from 350 nm to 780 nm (linear scale): A(λ) and the principle of determination of λ_(cut).

FIG. 2 is a schematic representation of various shapes (spheres and plates) and structure (homostructure, core/shell, core/crown, dot in plate) of semi-conductive nanoparticles.

FIG. 3 shows absorbance curves of dispersions of semi-conductive nanoparticles capped with organic compounds.

FIG. 4 shows absorbance curves of dispersions of semi-conductive nanoparticles capped with polymeric compounds.

FIG. 5 shows absorbance curves of lenses comprising semi-conductive nanoparticles.

FIG. 6 shows absorbance curves of lens comprising a Sol-Gel coating comprising semi-conductive nanoparticles.

FIG. 7 shows the absorbance curves of CdS nanoplates in heptane (semi-dotted line), of CdS-MPA nanoparticles in water (dotted line) and of lens comprising Diethylene glycol bis(allyl carbonate) and CdS nanoplates (solid line).

FIG. 8.1 shows the absorbance curves of ZnSe nanospheres in toluene (semi-dotted line), of encapsulated ZnSe nanospheres in methanol (dotted line) and of lens comprising a Sol-Gel coating comprising ZnSe nanospheres (solid line).

FIG. 8.2 shows the absorbance curves of ZnSe nanoplates in toluene (semi-dotted line), of encapsulated ZnSe nanoplates in methanol (dotted line) and of lens comprising a Sol-Gel coating comprising ZnSe nanoplates (solid line).

EXAMPLES

The present invention is further illustrated by the following examples.

Example 1: Semi-Conductive Nanoparticles

Dot in plate semi-conductive nanoparticles (hereafter DiP) of formula CdSe_(x)Si_(1-x), with x=0.3, comprising a CdSe_(0.5)S_(0.5) dot included in a nanoplate of CdS in which composition varies continuously from core to shell, having a thickness of 1.2 nm (corresponding to 4 monolayers), length of 15 nm and width of 20 nm were prepared according to procedure disclosed in European Patent EP2633102. A dispersion of DiP in heptane is obtained, referred to as dispersion D0.

Table 2 below discloses the absorbance of dispersion D0.

TABLE 2 λ_(max) 422 nm λ_(0.9) (at 0.9 * A_(max)) 427 nm λ_(0.5) (0.5 * A_(max)) 434 nm λ_(0.1) (0.1 * A_(max)) 446 nm |λ_(0.5) − λ_(0.9)|  7 nm |λ_(0.1) − λ_(0.9)|  19 nm

20 mL of a dispersion comprising DiP in heptane was heated in a round-bottom flask at 65° C. and 0.5 mL of 1-octanethiol was carefully added. The dispersion was kept at 65° C. for 3 hours. As thiols have strong affinity with Cadmium, 1-octanethiol forms an organic capping layer around DiP. The dispersion is then washed three times with absolute ethanol and heptane to remove any excess of capping compounds which may be present in the dispersion. In the end, this procedure allows the preparation a DiP dispersed in heptane, having only 1-octanethiol molecules as capping compounds. The dispersion is referred to as D8.

This procedure was repeated with 1-butanethiol instead of 1-octanethiol, yielding dispersion D4.

This procedure was repeated with 1-dodecanethiol instead of 1-octanethiol, yielding dispersion D12.

Another capping was also performed. A dispersion comprising 20 mL DiP in heptane was added in a round-bottom flask. 5 mL of absolute ethanol was added in order to precipitate all nanoplates. After solvent removal, these nanoplates were dispersed in 20 mL of toluene. 6 mL of a 0.1 M solution of cadmium bromide in toluene was then added. As Bromine anions have a strong affinity with Cadmium, they form a layer around DiP. This mixture was heated at 65° C. for 30 minutes and then washed three times with absolute ethanol and toluene, yielding a dispersion DBr.

Absorbance curves of 50 ppm of DiP in heptane were measured as a function of light wavelength in the UV-visible range before (dispersion D0) and after capping for dispersions D4, D8 and D12. Absorbance curves are displayed on FIG. 3.1 : D0 solid black line, D4 dotted black line, D8 solid grey line, D12 dotted grey line.

Absorbance curve of 50 ppm of DiP in toluene was measured as a function of light wavelength in the UV-visible range before and after capping for dispersions DBr. Absorbance curve of dispersion DBr is displayed as dotted line on FIG. 3.2 , with absorbance curve of dispersion D0 in solid line.

Wavelength of transition λ_(cut) was determined for all absorbance curves and reported in Table 3. One can observe that organic layers on semi-conductive nanoparticles induce a significant shift in λ_(cut). This is especially interesting to design semi-conductive nanoparticles with a pre-determined wavelength of transition.

TABLE 3 Dispersion λ_(cut) (nm) D0 409 D4 440 D8 440 D12 436 DBr 426

Example 2: Polymerizable Composition

Dot in plate semi-conductive nanoparticles (hereafter DiP) of formula CdSe_(x)S_(1-x), with x=0.3, comprising a CdSe_(0.5)S_(0.5) dot included in a nanoplate of CdS in which composition varies continuously from core to shell, having a thickness of 1.2 nm (corresponding to 4 monolayers), length of 15 nm and width of 20 nm were prepared according to procedure disclosed in European Patent EP2633102.

0.5 mL of a dispersion comprising DiP in 10 mM NaHCO₃ solution was mixed with 5 mg of a copolymer (DPn of 15-20) comprising 20 mol % of (5, 7-dimercapto)-N-(3-methacrylamidopropyl)heptanamide and 80 mol % poly(ethylene glycol) methyl ether methacrylate (Mn of 40) and kept under gentle stirring overnight at 60° C. Then sample was washed with ethanol and nanoparticles capped with polymer in ethanol was obtained. This dispersion A has a weight content in nanoparticles of 5%.

Absorbance curves of nanoparticles in ethanol were measured as a function of light wavelength in the UV-visible range before (dotted line) and after capping with polymer (solid line) and are shown on FIG. 4.1 . Below absorbance of 0.01, composition is transparent with no attenuation effect visible by eye.

One can observe that wavelength of transition λ_(cut), changes slightly when nanoparticles are capped with a polymer. However, the shape of absorbance curve is not changed. Transition from a transparent dispersion to a very absorbent dispersion is very sharp: absorbance decreases from 1 to 0.2 over about 25 nm.

70 mg of Benzoyl Peroxide (BPO, 50% weight in dicyclohexyl phthalate) was added in 2 mL of diallyl phthalate (DAP) yielding a solution B of 3 weight % of BPO catalyst in DAP monomer.

25 μL of dispersion A and 500 μL of solution B were mixed together under vortex for 10 seconds, then sonicated in degassing mode at 25° C. for 60 seconds, yielding the polymerizable composition C1. Weight content of semi-conductive nanoparticles in composition C1 was 45 ppm.

Same experiment was reproduced with semi-conductive nanoparticles of formula CdS and having a shape of nanoplates with thickness of 0.9 nm (corresponding to 3 monolayers), length of 15 nm and width of 20 nm, yielding a polymerizable composition C2 with weight content of semi-conductive nanoparticles of 45 ppm.

Absorbance curves of nanoparticles in ethanol were measured as a function of light wavelength in the UV-visible range before (dotted line) and after capping (solid line) with polymer and are shown on FIG. 4.2 .

A comparative polymerizable composition C_(comp) was prepared without semi-conductive nanoparticles.

Same experiment was reproduced with a mixture of semi-conductive nanoparticles: 0.3 mL of composition C1 and 0.5 mL of composition C2, yielding composition C3. Such a mixture allows to adapt the absorbance curve in the region of wavelength of transition λ_(cut) thereby providing a tool to fine tune optical performances of lenses obtained after polymerization.

Example 3: Lens

Polymerizable compositions C1, C2 and C3 were casted into moulds having centre thickness of 2 millimetres. The assembly was laid in an oven at 100° C. for 18 hours, then cooled and de-assembled, yielding respectively plastic samples S1, S2 and S3 of diameter about 2 cm.

A comparative sample S_(comp) was prepared form polymerizable composition C_(comp).

FIG. 5.1, 5.2, 5.3 show absorbance of samples S1, S2 and S3 (solid lines) as a function of light wavelength in the UV-visible range. On these figures, absorbance of sample S_(comp) (semi-dotted line) is added to highlight that absorbance of samples S_(n) is the sum of absorbance of polymerized DAP and absorbance of semi-conductive nanoparticles.

Absorbance and wavelength of transition λ_(cut) of semi-conductive nanoparticle used for composition C_(n) and sample S_(n) are almost the same, demonstrating that semi-conductive nanoparticles are not degraded during polymerization.

Besides, the characteristics of sample S1 for λ_(0.9), λ_(0.5) and λ_(0.1) are the same as the characteristics of dispersion of nanoparticles listed in table 2: incorporation of nanoparticles into polymerizable composition didn't change absorbance features

One can observe that absorbance is governed by semi-conductive nanoparticles in the range 380 nm-450 nm, while absorbance is governed by polymerized DAP in the range 450 nm-780 nm. Hence, decrease of the absorbance curve is less sharp on polymerized lenses due to intrinsic absorbance of polymerized DAP. If polymerized material was less absorbent, sharpness of decrease of absorbance curve would be restored.

Lenses obtained are transparent, i.e. there is no observable scattering and an object can be recognized when observed through the lens. However, these lenses absorb very efficiently high energy visible light with a very sharp transition in absorbance curve.

Example 4: Coatings

Semi-conductive nanoparticles of formula CdS and having a shape of plate with length of 20 nm; width of 40 nm and thickness of 1.5 nm (corresponding to 5 monolayers) were prepared according to procedure disclosed in EP2633102.

1 mL of a dispersion comprising CdS nanoplates in tetrahydrofuran was added in a round-bottom flask containing 4 mL of a diluted solution of 11-Mercapto-1-undecanol at 0.02 M in tetrahydrofuran. This mixture is then heated at 50° C. under reflux for 24 hours. As thiols have strong affinity with Cadmium, 11-Mercapto-1-undecanol forms an organic capping layer around CdS nanoplates. Nanoplates were recovered by centrifugation and washed three times with heptane and methanol. A 0.5 mL methanol dispersion of CdS nanoplates capped with 11-Mercapto-1-undecanol was obtained and called dispersion Dcoat. Dispersion Dcoat had a weight content in nanoparticles of 2.5%.

In addition, a Sol-Gel solution SG was also prepared in a separated vial with 100 μL of (3-Glycidyloxypropyl)trimethoxysilane, 65 μL of diethoxydimethylsilane and 35 μL of 0.1 M HCl. Solution SG was stirred for 24 hours at room temperature.

50 μL of dispersion Dcoat was added to 200 μL of solution SG to obtain a polymerizable composition then deposited by spin coating on a glass lens at 400 rpm during 30 s (dispensing step) then 2000 rpm during 2 min (spreading step). The resulting sample was then heated at 150° C. for 6 h in order to obtain a condensed 5 μm thick Sol-Gel coating having a weight content in CdS nanoplates of 1% after curing.

Absorbance curves of CdS nanoparticles in heptane (semi-dotted line), of CdS-mercapto-undecanol nanoparticles in methanol (dotted line) and of the coated glass lens (solid line) were measured as a function of light wavelength in the UV-visible and are shown on FIG. 6 . A wavelength of transition λ_(cut) of 445 nm is obtained for the coated glass lens.

Here again, one can observe that organic capping of nanoplates enables to change value of wavelength of transition λ_(cut) and that wavelength of transition is not changed after curing of the coating, demonstrating that semi-conductive nanoparticles withstand polymerization conditions without being degraded.

Example 5: Lens from Polymerizable Composition Comprising Diethylene Glycol Bis(Allyl Carbonate) Monomer and CdS Nanoplates

Semi-conductive nanoparticles of formula CdS and having a shape of plate with length of 10 nm; width of 20 nm and thickness of 0.9 nm (corresponding to 3 monolayers) were prepared according to procedure disclosed in EP2633102.

5 mL of a dispersion comprising CdS nanoplates were mixed with 2 mL of 3-mercaptoproprionic acid (MPA). This mixture was heated at 60° C. for 2 hours. Nanoplates were recovered by centrifugation and washed three times with ethanol and toluene. CdS nanoplates capped with MPA were redispersed in water at pH=10. This dispersion is called dispersion D4. Dispersion D4 had a weight content in nanoparticles of 0.5%. Nanoparticles of dispersion D4 were encapsulated according to the procedure disclosed in EP3630683 within a silica shell.

Table 4 below discloses the absorbance of dispersion D4.

TABLE 4 λ_(max) 400 nm λ_(0.9) (at 0.9 * A_(max)) 402 nm λ_(0.5) (0.5 *A_(max)) 406 nm λ_(0.1) (0.1*A_(max)) 410 nm |λ_(0.5) − λ_(0.9)|  4 nm |λ_(0.1) − λ_(0.9)|  8 nm

10 mg of encapsulated CdS nanoplates of dispersion D4 were mixed with 1.65 mL of Diethylene glycol bis(allyl carbonate) and 100 mg of diisopropyl peroxydicarbonate (IPP) initiator. A homogeneous mixture is obtained by sonication in degassing mode at 25° C. for 60 seconds, yielding the polymerizable composition C4.

Polymerizable composition C4 was casted into moulds having centre thickness of 2 millimetres. The assembly was laid in an oven at 100° C. for 18 hours, then cooled and de-assembled, yielding plastic sample S4 of diameter about 2 cm.

Absorbance curves of CdS nanoplates in heptane (semi-dotted line), of CdS-MPA nanoparticles in water (dotted line) and of sample S4 (solid line) were measured as a function of light wavelength in the UV-visible and are shown on FIG. 7 . A wavelength of transition λ_(cut) of 399 nm is obtained for sample S4.

Besides, the characteristics of sample S4 for λ_(0.9), λ_(0.5) and λ_(0.1) are the same as the characteristics of dispersion of nanoparticles listed in table 4: incorporation of nanoparticles into polymerizable composition didn't change absorbance features

Sample S4 is a transparent lens, i.e. there is no observable scattering and an object can be recognized when observed through the lens. However, these lenses absorb very efficiently high energy visible light with a very sharp transition in absorbance curve.

Example 6: Coatings Comprising ZnSe Nanospheres and Nanoplates

Semi-conductive nanoparticles of formula ZnSe and having a shape of sphere with diameter of 5.8±0.2 nm were prepared according to procedure known in the art and reported in New J. Chem., 2007, 31, 1843-1852.

5 mL of a dispersion comprising ZnSe nanospheres were mixed with 5 mL of 3-mercaptoproprionic acid (MPA). This mixture was heated at 60° C. for 2 hours. The nanospheres were recovered by centrifugation and washed three times with absolute ethanol and toluene. ZnSe nanospheres capped with MPA were redispersed in water at pH=10. These nanospheres were encapsulated according to the procedure disclosed in EP3630683 within a silica shell and redispersed in 0.5 mL of methanol. This dispersion was called dispersion D5 and had a weight content of 2.5% of nanospheres.

Table 5 below discloses the absorbance of dispersion D5.

TABLE 5 λ_(max) 424 nm λ_(0.9) (at 0.9 * A_(max)) 428 nm λ_(0.5) (0.5 *A_(max)) 432 nm λ_(0.1) (0.1 *A_(max)) 440 nm |λ_(0.5) − λ_(0.9)|  4 nm |λ_(0.1) − λ_(0.9)|  12 nm

Same experiment was reproduced with semi-conductive nanoparticles of formula ZnSe and having a shape of nanoplates with thickness of 1.9 nm (corresponding to 5 monolayers), length of 15 nm and width of 30 nm. These nanoplates were prepared according to procedure known by the man of the art and reported in Mater. Lett. 2013, 99, 172-175. ZnSe nanoplates were capped with MPA and were redispersed in water at pH=10. These nanoplates were encapsulated according to the procedure disclosed in EP3630683 within a silica shell and redispersed in 0.5 mL of methanol. This dispersion was called dispersion D6 and had a weight content of 2.5% of nanoplates.

In addition, a Sol-Gel solution SG was also prepared in a separated vial with 100 μL of (3-Glycidyloxypropyl)trimethoxysilane, 65 μL of diethoxydimethylsilane and 35 μL of 0.1 M HCl. Solution SG was stirred for 24 hours at room temperature.

50 μL of dispersion D5 were added to 200 μL of solution SG to obtain a polymerizable composition then deposited by spin coating on a glass lens at 400 rpm during 30 s (dispensing step) then 2000 rpm during 2 min (spreading step). The resulting sample S5 was then heated at 150° C. for 6 h in order to obtain a condensed 5 μm thick Sol-Gel coating having a weight content in ZnSe nanospheres of 1% after curing.

Same experiment was reproduced with encapsulated ZnSe nanoplates. 50 μL of dispersion D6 were added to 200 μL of solution SG to obtain a polymerizable composition then deposited by spin coating on a glass lens at 400 rpm during 30 s (dispensing step) then 2000 rpm during 2 min (spreading step). The resulting sample S6 was then heated at 150° C. for 6 h in order to obtain a condensed 5 μm thick Sol-Gel coating having a weight content in ZnSe nanoplates of 1% after curing.

Absorbance curves of ZnSe nanospheres in toluene (semi-dotted line), of encapsulated ZnSe nanospheres in methanol (dotted line) and of the coated glass lens S5 (solid line) were measured as a function of light wavelength in the UV-visible and are shown on FIG. 8.1 . A wavelength of transition λ_(cut) of 410 nm is obtained for sample S5.

Besides, the characteristics of sample S5 for λ_(0.9), λ_(0.5) and λ_(0.1) are the same as the characteristics of dispersion of nanoparticles listed in table 5: incorporation of nanoparticles in Sol-Gel coating didn't change absorbance features

Absorbance curves of ZnSe nanoplates in toluene (semi-dotted line), of encapsulated ZnSe nanoplates in methanol (dotted line) and of the coated glass lens S6 (solid line) were measured as a function of light wavelength in the UV-visible and are shown on FIG. 8.2 . A wavelength of transition λ_(cut) of 401 nm is obtained for sample S6. 

1.-14. (canceled)
 15. A polymerizable composition for the manufacture of an ophthalmic lens, comprising: (a) at least one monomer or oligomer; (b) at least one catalyst for initiating the polymerization of said monomer or oligomer; and (c) semi-conductive nanoparticles which are dispersed in said monomer or oligomer, wherein the absorbance through a 2-millimeter thick layer of said polymerizable composition is higher than 0.5 for each light wavelength ranging from 350 to λ_(cut), λ_(cut) being in the visible range.
 16. The polymerizable composition according to claim 15, wherein λ_(cut) is in the range from 400 nm to 480 nm.
 17. The polymerizable composition according to claim 15, wherein monomer is an allyl monomer or an allyl oligomer.
 18. The polymerizable composition according to claim 15, wherein the catalyst is a free radical initiator.
 19. The polymerizable composition according to claim 15, wherein monomer is an alkoxysilane.
 20. The polymerizable composition according to claim 18, wherein the catalyst is a Lewis acid.
 21. The polymerizable composition according to claim 15, wherein the semi-conductive nanoparticles comprise a material of formula M_(x)Q_(y)E_(z)A_(w)  (I), wherein: M is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; Q is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; E is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; A is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; and x, y, z and w are independently a decimal number from 0 to 5; x, y, z and w are not simultaneously equal to 0; x and y are not simultaneously equal to 0; z and w may not be simultaneously equal to
 0. 22. The polymerizable composition according to claim 15, wherein the semi-conductive nanoparticles are nanospheres, nanoplates or nanorods.
 23. The polymerizable composition according to claim 15, wherein the semi-conductive nanoparticles are core/shell particles or core/crown particles, the core being a different material from the shell or crown.
 24. The polymerizable composition according to claim 15, wherein the amount of semi-conductive nanoparticles in the composition is from 10 ppm to wt %, based on the weight of the polymerizable liquid composition.
 25. The polymerizable composition according to claim 15, wherein the semi-conductive nanoparticles are capped with an organic layer or encapsulated in an inorganic matrix.
 26. A process for the preparation of the polymerizable composition as defined in claim 15, comprising the steps of: (a) providing a monomer or oligomer; (b) providing semi-conductive nanoparticles in the form of a powder dispersible within said monomer or oligomer or in the form of a dispersion of said semi-conductive nanoparticles in a liquid dispersible within said monomer or oligomer; (c) providing a catalyst for initiating the polymerization of said monomer or oligomer; and (d) mixing said monomer or oligomer, said semi-conductive nanoparticles and said catalyst.
 27. An ophthalmic lens obtained by curing the polymerizable composition as defined in claim
 15. 28. An ophthalmic lens comprising: (a) an optical substrate; and (b) a coating obtained by curing the polymerizable composition as defined in claim 15 on said optical substrate.
 29. An ophthalmic lens according to claim 28, wherein the absorbance through a 2-millimeter thick ophthalmic lens is higher than 0.5 for each light wavelength ranging from 350 to λ_(cut), λ_(cut) being in the visible range.
 30. The ophthalmic lens according to claim 29, wherein λ_(cut) is in the range from 400 nm to 480 nm. 